1. Field of Invention
The invention relates to a method for testing the resistance of the HIV-2 virus to antiprotease treatment in a patient infected with HIV-2 as well as nucleotide probes usable for such testing.
2. Description of Related Art
Acquired immunodeficiency syndrome (AIDS) is caused by two viruses: HIV-1 and HIV-2. HIV-1 is present throughout the world while HIV-2 is present mainly in western Africa.
Effective antiviral treatments have been in widespread use since 1996 in developed countries where the virus present is HIV-1. Because of their cost, these treatments cannot be used in developing countries where HIV-2 is present.
There are three types of antiretroviral treatments: antiprotease (Indinavir, Ritonavir, Saquinavir, Nelfinavir, and Amprenavir), nucleoside reverse transcriptase (RT) inhibitors (Zidovudine, Didanosine, Zalcitabine, Lamivudine, Stavudine, Abacavir, FTC, and Adefovir), and nonnucleoside RT inhibitors (Nevirapine, Delavirdine, and Efavirenz). These treatments are often given in combination; this is known as multiple-drug therapy.
Antiproteases elicit primary mutations which confer a high degree of resistance but alter the ability of the virus to replicate. Thus, the virus needs to select secondary mutations if it is to be both resistant and able to replicate actively. Also, reverse transcriptase mutations have been described where nucleoside RT inhibitors have been used in combination.
During treatment with HIV-1 infection, particularly if the levels of drug in the bloodstream are inadequate, viral replication is insufficiently inhibited, or rises above the detection threshold of available viral load techniques (the “viral load” measures the quantity of virus genomes in the bloodstream). Because of the high error rate of reverse transcription, mutations take place in the genes targeted by protease and reverse transcriptase treatment. Certain mutations bring about various degrees of resistance to antivirals. Virologic failure occurs in 20 to 40% of patients treated with current multiple drug regimens.
If viruses resistant to one or more substances can be shown for a patient before treatment or if the viral load increases again, the best drug combination for treating HIV-1 can be chosen.
There are currently no published data on mutations in the HIV-2 genome due to the use of antiproteases.
Antiprotease agents that are active against HIV-1 are also active against HIV-2. However, there are no methods available to assist the clinician in determining resistance to antiprotease drugs in patients infected with HIV-2.